1. Field of the Invention
The present invention relates to a method of manufacturing an active matrix substrate using a method of transferring a thin film device. The present invention also relates to an active matrix substrate manufactured by the manufacturing method, and a liquid crystal display device comprising this active matrix substrate as one of a pair of substrates.
2. Description of Related Art
For example, a liquid crystal display using thin film transistors (TFT) is manufactured through the step of forming thin film transistors on a substrate by CVD or the like. Since the step of forming thin film transistors on the substrate is accompanied with high temperature processing, it is necessary to use material for the substrate which has excellent heat resistance, i.e., material having a high softening point and melting point. At present, silica glass is used as a substrate which can resist a temperature of about 10000C, and heat resistant glass is used as a substrate which can resist a temperature of about 500° C.
Namely, the substrate on which thin film elements are mounted must satisfy conditions for producing the thin film transistors. Therefore, the substrate used is determined so as to satisfy conditions for manufacturing a device to be mounted thereon.
However, in consideration of only the steps after the substrate comprising the thin film transistors such as TFT or the like mounted thereon is completed, in some cases, the above-described substrate is not always satisfactory.
For example, in the above-described manufacturing process accompanied with high temperature processing, a quartz substrate, a heat-resistant substrate, or the like is used. However, these substrates are very expensive, and thus cause an increase in product cost.
Also the glass substrate has the properties that it is heavy and easily broken. A liquid crystal display used for portable electronic apparatus such as a palm top computer, a portable telephone, etc. is preferably light weight, can resist a little deformation, and is hardly broken by dropping. However, in fact, the glass substrate is generally heavy, less resistant to deformation and is possibly broken by dropping.
In other words, there are gaps between the limitations caused by manufacturing conditions and preferable characteristics required for products, and it is very difficult to satisfy the conditions and characteristics.